Not all optical devices from my collection were described in my articles and today I want to talk a little about the ZRT-454 spyglass.
The pipe is very rare and almost never found on sale. Its price can reach up to 700-1000 US dollars (in terms of the exchange rate). Information about it is practically absent in open sources. I wrote a letter to the factory that produced it, but they could not provide any information about it and its production, they did not even find instructions from it. Perhaps they were just too lazy to go to the archive.
The device was produced at the Kazan Optical and Mechanical Plant in the 70s of the twentieth century. The exact period of production and the number of issued copies is unknown. Most likely, the device was not available for retail sale and was delivered to shooting galleries and military units, to landfills.
The optical scheme of the tube is shown in the figure. Designations: 1 - meniscus, 2 - primary mirror, 3 - secondary mirror, 4 - reversing and corrective system, 5 - eyepiece.
The tube is a mirror-lens meniscus system with a lens inverting system. D=130mm; F=1000mm; G=25x; 50x; 80x; (100x), change of magnification is carried out by connecting three eyepieces mounted on the turret in series. Magnification of 25x is achieved with a Kellner eyepiece, the remaining magnifications are achieved with wide-angle eyepieces with a removed pupil. A feature of the pipe is the use of Mangin mirrors with an internal coating. Such a mirror is a combination of a mirror and a negative lens. The secondary mirror covers only 4% of the area of the entrance pupil. The tube is very compact, mounted on an azimuthal fork. Available with cast table stand or field tripod. Movements along the axes are carried out using gear (azimuth) and worm (height) gears. The ocular head is moved with the help of a rack. The eyepieces have a diopter. The system has a high resolution and gives a direct image of the object.
For astronomy, this telescope is of little use - the short feathers of the fork will not allow it to be aimed at an object located high above the horizon. I could not remove the pipe from the plug, perhaps a one-piece connection is used there and I was afraid to break something.
During shipment, the pipe was slightly damaged and the alignment was knocked down. For repair and adjustment, I had to disassemble it, and I was surprised to find that the adjusting screws at the meniscus and the main mirror were not provided for by the design. Optics in frames are simply screwed into the pipe along the thread.
In general, this is a rather interesting device with a very unusual optical design. I don't know if something similar was produced somewhere else in the world.
Edited by Petsyk Alexey, 15 January 2023 - 01:15 AM.